I would think that you would not be allowed to deduct the full $500 because you are getting a service — the ability to "skip the line" and grab a graphics card. You can only deduce $500 - FMV of that service, which a reasonable person might say is the difference between the street price of the scalped non-DWB cards and the DWB cards.

If the street price of the scalped cards is higher than the DWB edition, then you would not be able to deduct anything.